Combustion control device

ABSTRACT

A device for controlling the variation of power stage of the gas burners as a function of the variation of the pressure of the feed gas characterized by a pressure sensitive device which in response to two or more values of the gas pressure will close or open circuits which, by means of the predisposed programs on the control board, will act on the power operated valve or electrovalve that chokes the gas, and will adjust the gas feed changing the power state of the burner.

United States Patent [191 Massi [11] 3,843,310 1 Oct. 22, 1974 1COMBUSTION CONTROL DEVICE [76] Inventor: Giovanni Massi, No. 24, Via

Genova, Rome, Italy [22] Filed: Sept. 4, 1973 211 Appl. No.: 394,196

[30] 7 Foreign Application Priority Data Sept 6, 1972 Italy 52583/72.lan. 29, 1973 Italy 47955/73 [52] US. Cl. 431/90, 137/4875 [51] Int.Cl. F23n 1/02 [58] Field of Search 431/89, 90, 12; 137/486, 137/487.5

[56] References Cited UNITED STATES PATENTS 3,542,060 11/1970 Niehhuis137/4875 3,549,089 12/1970 Hamlett 431/12 3749,5461 7/1973 Reed et al 1431/89 X 3,765,444 10/1973 Kosugi 137/486 Primary Examiner-Edward G.Favors Attorney, Agent, or Firm-Hill, Gross, Simpson, Van

Santen, Steadman, Chiara & Sampson [57] ABSTRACT A device forcontrolling the variation of power stage i of the gas burners as afunction of the variation of the pressure of the feed gas characterizedby a pressure sensitive device which in response to two or more valuesof the gas pressure will close or open circuits which, by means of thepredisposed programs on the control board, will act on the poweroperated valve or electrovalve that chokes the gas, and will adjust thegas feed changing the power state of the burner.

8 Claims 6 Drawing Figures PMENTED 0m 22 1974 v SHEEI 2 BF 3 COMBUSTIONCONTROL DEVICE The present invention relates to a device to be appliedto the burners for town gas for controlling the combustion during thepeaks of maximum'absorption from the distribution network.

The purpose of this invention is that of obtaining the automaticreduction of the fuel request or demand by the gas burners when thepressure in the town distribution network decreases below the usualvalues due to an excess of request or demand. I

Another purpose is to maintain the ratio of the airgas mixture in theblown air burners, when the pressure changes, and therefore changes therate of flow of the gas, so as to obtain both optimum efficiencies forthe burners and a correct combustion therein.

At present, the blownairburners do not adjust the amount of the airsupporting the combustion to compensate for changes in gas pressure.Thus, any changes in the rate of flow of the fuel is not adjusted by theamount of air being introduced by the burner.

In the distribution networks of the towns, onthe contrary, periodicalfalls and raisings of the gas pressure occur as a function of the demandon the distribution network of the gas distributing system. The amountof fluctuation to an individual consumer also depends on the location ofthe consumer in the network.

The stabilization of the pressure by means of reducers stabilizerscreates losses of pressure which, during the moments of maximumabsorption or demand, add to the losses whichalready exist in the cuts,to increase the possibility of jamming of the burners. Moreover, theexcessive variations of gas pressure, and therefore of the rate of flowof the fuel, causes a variation of the ratio of air-gas mixtureandthereby an irregular combustion which causes. a decrease of theefficiency, the formation of carbon monoxide, and the possibility ofjammings due to intervention of the flame detector.

The present invention provides a device for overcoming said drawbacks,by reducing automatically the power required by the burner when thepressure in the gas distributing network diminishes, and by adjustingthe rate of flow of the combustion supporting air, to each rate of flowof the fuel, so as to maintain the airgas mixture within the limits orratio which is necessary for a correct combustion of the fuel.

In the drawings:

FIG. 1 diagrammatically illustrates the device according to thisinvention applied to a blow-air burner;

FIG. 2 illustrates an embodiment of the device of FIGJ; I

FIG. 2A is a side view of the burner of FIG. 2

FIG. 2B is a plan view with portions in cross section of the burner ofFIG. 2A;

FIG. 2C is a plan view of the contral valves and connecting conduits forthe burner of FIG. 2B;

FIG. 3 diagrammatically illustrates the invention when applied to aburner of the socalled atmospheric type. 3

DESCRIPTION OF THE PREFERRED EMBODIMENTS 1 As illustrated, the gas flowis received by a cut-off faucet or valve 1 which is connected to asafety electrovalve 2. A pressure switch 3 is associated with the valve2 and operates in case of a lack of gas pressure to close the valve 2.From; valve 2, the gas flows through a conduit to a multiple positionelectrovalve or power operated valve 4 which is associated with acontrol valve or faucet 5. A by-pass conduit or line 11 is connected toa Tee provided in the conduit extending between valves 2 and 4 and theby-pass conduit is provided with an electrovalve 7 and a contral valveor faucet 8. The bypass conduit supplies gas to the pilot flame of aburner head 6 of the burner; The head 6 is received in a tubular part ofa casing 12 of the burner (FIG. 2B). As illustrated in FIG. 1, thecasing 12 contains an air choking valve 9 whose setting is controlled bymeans of a mechanical linkage interconnecting the valve 9 to the valve4.

This invention provides a pressure sensitive element 10 which hascontacts 13. When the pressure is normal, the element 10 allows theburner to operate according to its usual characteristic cycle, whichincludes preheating, starting, continuous running and shut off stages.Under a reduced pressure, which has a value determined or pre-selectedby adjustments provided with the element 10, the contacts 13 of theelement 10 will open a circuit of a control board which applies apartial choking program on the valve 4 and also shut-off the valve 7 ofthe by-pass. Thus, the burner will operate at reduced rate of flow forthe running stage and this reduced ratecan be pre-established at will byacting on the adjustment of the main valve 4.. Simultaneously, themechanical control linkage, which interconnects the air choking valve .9to the valve 4, willadjust the air choking'valve 9 to adjust the amountof air being supflow of combustion supporting air would correspond.

Thisdrawback will be automatically removed by the control mechanismwhich by means of the closure of the contacts 13 will provide a partialshut-off of the valve 4 and total shut-off of the valve 7 to therebyprevent an excessive amount of gas from reaching the burner.

In the embodiment of FIG. 2, the air choking valve 9 is connected to apower operated adjusting device M controlled by a servo 14 associated tothe valve 4. When the valve 4 controls the rate of flow to the burner,the valve 4 by means of the servo 14 and device M controls the settingof the air choking valve.

In case of an induced air burner 15 (FIG. 3) which burners are alsocalled atmospheric burners or sucked air burners, the pressure sensitiveelement 10 is inserted upstream of the atmospheric burner 15 in theconduit extending thereto. The position, which is shown in FIG. 3, isonly for exemplary purposes. The position of the element 10 in theconduit can change in relation to the adjusting valve 4, shut-off valve1 and safety device 2 which are provided for the various kinds ofburners and to which the burner can be associated.

The sensitive element by means of an electric or mechanical connection,or a connection of another kind, acts on the choking valve 4 compelingit to take a reduced aperture position, when the gas pressure decreasesunder a normal value, which is pre-established by setting of theadjustment on'the sensitive element 10. When the value of the gaspressure is above a normal preestablished value, the element 10 willalso transmit a control function to the valve 4.

Althoughminor modifications might be suggested by those versed in'theart, it should be understood that I wish to employ within the scope ofthe patent warranted herein all such modifications as reasonably andproperly come within the scope of my contribution to the art.

I claim:

1.'A device for'cont rolling the variations of a power stage of a gasburner as a function of the variation of the pressure of the gas beingsupplied thereto, said device comprising an electrovalve for choking theflow of gas in a conduit extending to the burner, a pressure sensitivedevice arranged to sense the pressure of the gas flowing in saidconduit, and circuit means interconnecting said pressure sensitivedevice and the electrovalve which circuit means include a control boardcontaining a predetermined program, said pressure sensitive device inresponse to at least two values of said gas pressure opening and closingsaid circuits to actuate the electrovalve so that the rate of gas feedto the burner is adjusted to change the power state thereof, said burnerconduit having a by-pass line extending to a head of the burner toprovide a pilot flame, said bypass link including means for controllingflow therethrough, and wherein said pressure sensitive element alsocontrols operation of the means for controlling flow in the by-pass linein response to the sensed pressure to enhance the variation in the rateof flow caused by operation of the electrovalve.

2. A device according to claim 1, wherein said burner is a blown airburner having an air inlet duct provided with a choking valve forregulating the flow of air through the inlet and wherein saidelectrovalve includes means for adjusting the setting of the chokingvalve in response to changes in the rate of gas flow through saidelectrovalve so that the desired air-gas ratio for maximum combustionefficiency is maintained for variation in the amount of gas supplied tothe burner. I

3. A device according to claim 2, wherein said means for adjustingcomprises a power operated adjusting device on said choking valve and aservo attached to said electrovalve to control said adjusting device.

4. A device according to claim 2, wherein said means for adjustingcomprises a mechanical linkage interconnecting the choking valve to theelectrovalve.

5. A device for controlling the variations of a power stage of a gasburner as a function of the variation of the pressure of the gas beingsupplied thereto, comprising an electrovalve for choking the flow of gasin a conduit extending to a head of the burner, said conduit having aby-pass line to provide a pilot flame and including means forcontrolling flow therethrough and a pressure sensitive element arrangedto sense the pressure of the gas flowing in said conduit and to controlthe operation of said means for controlling the flow in the by-pass linein response to the sensed pressure to enhance the variation in the rateof flow caused by operation of said electrovalve.

6. A device according to claim 5, wherein said burner is a blown airburner having an air inlet duct provided with a choking valve forregulating the flow of air through the inlet and wherein saidelectrovalve includes means for adjusting the setting of the chokingvalve in response to changes in the rate of gas flow through saidelectrovalve so that the desired air-gas ratio for maximum combustionefficiency is maintained necting the choking valvev to the electrovalve

1. A device for controlling the variations of a power stage of a gasburner as a function of the variation of the pressure of the gas beingsupplied thereto, said device comprising an electrovalve for choking theflow of gas in a conduit extending to the burner, a pressure sensitivedevice arranged to sense the pressure of the gas flowing in saidconduit, and circuit means interconnecting said pressure sensitivedevice and the electrovalve which circuit means include a control boardcontaining a predetermined program, said pressure sensitive device inresponse to at least two values of said gas pressure opening and closingsaid circuits to actuate the electrovalve so that the rate of gas feedto the burner is adjusted to change the power state thereof, said burnerconduit having a by-pass line extending to a head of the burner toprovide a pilot flame, said by-pass link including means for controllingflow therethrough, and wherein said pressure sensitive element alsocontrols operation of the means for controlling flow in the by-pass linein response to the sensed pressure to enhance the variation in the rateof flow caused by operation of the electrovalve.
 2. A device accordingto claim 1, wherein said burner is a blown air burner having an airinlet duct provided with a choking valve for regulating the flow of airthrough the inlet and wherein said electrovalve includes means foradjusting the setting of the choking valve in response to changes in therate of gas flow through said electrovalve so that the desired air-gasratio for maximum combustion efficiency is maintained for variation inthe amount of gas supplied to the burner.
 3. A device according to claim2, wherein said means for adjusting comprises a power operated adjustingdevice on said choking valve and a servo attached to said electrovalveto control said adjusting device.
 4. A device according to claim 2,wherein said means for adjusting comprises a mechanical linkageinterconnecting the choking valve to the electrovalve.
 5. A device forcontrolling the variations of a power stage of a gas burner as afunction of the variation of the pressure of the gas being suppliedthereto, comprising an electrovalve for choking the flow of gas in aconduit extending to a head of the burner, said conduit having a by-passline to provide a pilot flame and including means for controlling flowtherethrough and a pressure sensitive element arranged to sense thepressure of the gas flowing in said conduit and to control the operationof said means for controlling the flow in the by-pass line in responseto the sensed pressure to enhance the variation in the rate of flowcaused by operation of said electrovalve.
 6. A device according to claim5, wherein said burner is a blown air burner having an air inlet ductprovided with a choking valve for regulating the flow of air through theinlet and wherein said electrovalve includes means for adjusting thesetting of the choking valve in response to changes in the rate of gasflow through said electrovalve so that the desired air-gas ratio formaximum combustion efficiency is maintained for variation in the amountof gas supplied to the burner.
 7. A device according to claim 6, whereinsaid means for adjusting comprises a power operated adjusting device onsaid choking valve and a servo attached to said electrovalve to controlsaid adjusting device.
 8. A device according to claim 6, wherein saidmeans for adjusting comprises a mechanical linkage interconnecting thechoking valve to the electrovalve.